Diaphragm pumps

ABSTRACT

A diaphragm pump comprising a drive shaft, a plurality of cylinders whose axes are equi-angularly spaced about the drive shaft axis and each of which axes is normal to the drive shaft axis, a piston received by each cylinder and reciprocable by means coupled to the drive shaft, each cylinder being in communication with a pressure chamber, each pressure chamber being defined by a tubular body and the external surface of a tubular diaphragm received by the tubular body, tbe tubular bodies having their axes parallel to the drive shaft axis and having a one way inlet valve and a one way outlet valve adjacent respective ends of the diaphragm and communicating with the interior thereof, each pressure chamber and associated cylinder being adapted to be filled with liquid whereby upon rotation of the drive shaft, liquid will be displaced between the pressure chambers and their associated cylinders by displacement of the pistons causing the cross sectional areas of the diaphragms to vary thereby to vary the volume and the pressure within the diaphragms to cause displacement of liquid therethrough.

United States Patent 1 Hart 1 1 Jan. 7, 1975 DIAPHRAGM PUMPS Bernard Eaton Hart, Rosebank, Stoford, near Salisbury, England 22 Filed: Nov. 24, 1972 [21] Appl. No.: 309,107

[76] Inventor:

[30] Foreign Application Priority Data Primary ExaminerWilliam L. Freeh Attorney, Agent, or Firm-Brisebois & Kruger [57] ABSTRACT A diaphragm pump comprising a drive shaft, a plurality of cylinders whose axes are equi-angularly spaced about the drive shaft axis and each of which axes is normal to the drive shaft axis, a piston received by each cylinder and reciprocable by means coupled to the drive shaft, each cylinder being in communication with a pressure chamber, each pressure chamber being defined by a tubular body and the external surface of a tubular diaphragm received by the tubular body, the tubular bodies having their axes parallel to the drive shaft axis and having a one way inlet valve and a one way outlet valve adjacent respective ends of the diaphragm and communicating with the interior thereof, each pressure chamber and associated cylinder being adapted to be filled with liquid whereby upon rotation of the drive shaft, liquid will be displaced between the pressure chambers and their associated cylinders by displacement of the pistons causing the cross sectional areas of the diaphragms to vary thereby to vary the volume and the pressure within the diaphragms to cause displacement of liquid therethrough.

17 Claims, 5 Drawing Figures SHEET 2 BF 2 PATENIEB JAN 7:975

DIAPHRAGM PUMPS This invention is concerned with improvements in and relating to diaphragm pumps, more particularly though not exclusively intended for pumping water at relatively high pressures such as, for example, 3,000 lbs per square inch.

According to one aspect of this invention there is provided a diaphragm pump comprising a drive shaft, a plurality of cylinders whose axes are equiangularly spaced about the drive shaft axis and each of which axes is normal to the drive shaft axis, a piston received by each cylinder and reciprocable by means coupled to the drive shaft, each cylinder being in communication with a pressure chamber, each pressure chamber being defined by a tubular body and the external surface of a tubular diaphragm received by the tubular body, the tubular bodies having their axes parallel to the drive shaft axis and having a one way inlet valve and a one way outlet valve adjacent respective ends of the diaphragm and communicating with the interior thereof, each pressure chamber and associated cylinder being adapted to be filled with liquid whereby upon rotation of the drive shaft, liquid will be displaced between the pressure chambers and their associated cylinders by displacement of the pistons causing the cross sectional areas of the diaphragms to vary thereby to vary the volume and the pressure within the diaphragms to cause displacement of liquid therethrough.

Each diaphragm preferably is normally unstressed in the tubular form and at present it is preferred that each receives a mandrel which provides axially extending angularly spaced support surfaces for the diaphragm and reduces the radial displacement of the unsupported area of the diaphragm.

An embodiment of the present invention will now be described, by way of example only, reference being had to the accompanying drawings, in which:

FIG. I is a partially sectioned plan view of a diaphragm pump;

FIG. 2 is a section along the line A A of FIG. 1;

FIGS 3A and 38 each comprise a section along the line B-B of FIG. 1 showing various configurations of the diaphragm, and

FIG. 4 is a section along the line C-C of FIG. 1.

As shown in the drawings the pump comprises a drive shaft 1 running in suitable bearings 2, 3 set in opposite walls of a casing 4. The drive shaft carries an eccentric 5 received by a needle bearing 5a on which are re tained, by an annular member or ring 5b, equiangularly spaced lugs 6 to each of which is pivotally coupled, by a pin 7, a piston 8 received by a cylinder 9. The cylinders are equi-angularly spaced about the drive shaft axis and each cylinder axis is normal to the drive shaft axis.

Each cylinder 9 is formed by a radial extension from a tubular body 10 the internal surface of which, together with the external surface of a tubular diaphragm 11, defines a pressure chamber 12. The diaphragm, for example of rubber, plastics or an elastomer, is anchored at each end between an internally frustoconical seat 13 on the tubular body and an externally frustoconical surface of an annular projection 14 carried by a valve seat insert 15. The valve seat insert 15a at one end of the diaphragm has an internally facing seat 16 for a ball 17 while the other valve seat insert 15b has an externally directed seat 18 for a ball 19. Conventional angularly spaced projections 20 on the valve seat insert serve to retain each ball when off its seat and to allow passage of liquid.

In FIG. 1 the lower (as drawn) internally frustoconical surface of the tubular body 10 is provided by a surface of a body insert 21 which is retained by the valve seat insert, itself held by a nut 22 threaded on to the body. This allows the tubular body to be machined through that end. The other internally frusto conical surface is shown as formed on the tubular body itself. It may however also be formed by a surface of an insert set in the tubular body and retained by the valve seat insert and nut 23.

The pump is designed to run with the axis of the drive shaft horizontal, vertical or at an inclination therebetween. Preferably the inclination to the horizontal is not less than about 5. The preferred inclination of the axis of the drive shaft is 45 to the horizontal. To bleed each pressure chamber 12 a bleed valve 24 is provided at what will be the uppermost region of that chamber. In FIG. 1 the bleed valve is shown set appropriately for that body to be at top dead centre. The appropriate position for the valve at the diametrically opposite position is indicated by the line 25. Instead of a bleed valve there may be a drill hole 26 (shown positioned as if the body were at bottom dead centre), closed by a sealing ring 27 retained by a nut 28 threaded on to the body.

The casing 4 is two part and the tubular bodies are retained in the casing by nuts 29 and shoulders 30, appropriate sealing rings 31 being provided. The casing is filled with oil which also fills the cylinders and pressure chambers by passage through ports 32 in the pistons. The casing includes a filler plug 33 which will be at or near top dead centre and may be vented to atmosphere.

In operation, the drive shaft, here shown as directly driven through a coupling 34, will, through the eccentric balanced by weights 35, reciprocate the pistons which will displace oil between the pressure chambers and cylinders thereby causing each diaphragm to collapse and re-open which action will drive water out through the outlet and draw water in through the inlet respectively. The pump may be run at speeds of the order of 950 to 1,500 r.p.m.

To control the form which each diaphragm takes when collapsing, a mandrel is inserted in each diaphragm. Two configurations of mandrel which may be used are shown in FIGS. 3A and 3B. In FlG. 3A there is shown a four lobe mandrel 36 whose lobes 37 extend axially to the annular projections 14 and beyond the central part of the mandrel to define flow paths at each end of the mandrel to the valve seats. The four lobe configuration is particularly suited to high lift. ln FIG. 38 there is shown a three lobe mandrel 38 with three lobes 39 and suitable for moderate lift. A mandrel with more than four lobes may be provided depending on the requirements of the pump.

The form of collapse of a diaphragm 11 under pres sure will be modified by the presence of the mandrel 36 or 38. The more lobes the mandrel possesses, the shorter the arc of the tubular diaphragm between each lobe and hence the higher its resistance to collapse and the higher its readiness to recover its original shape when the piston is withdrawn. This higher speed of response may be necessary at higher pump shaft speeds.

The mandrel 36 or 38 within a diaphragm l1 displaces volume which would otherwise remain unswept" when the tubular diaphragm is deflected, so

rials, and, since the diaphragms are not making any I sealing contact over their length, the bodies do not require a high degree of finish except at sealing regions. Each body 10 may be cast and from common castings bodies can be made up to suit the particular location around the casing by appropriate drilling for venting either by bleed valves or by externally sealed drill holes.

What I claim is:

l. A diaphragm pump comprising a drive shaft, a plurality of cylinders whose axes are equi-angularly spaced about the drive shaft axis and each of which axes is normal to the drive shaft axis, a piston received by each cylinder and reciprocable by means coupled to the drive shaft, each cylinder being in communication with a pressure chamber, each pressure chamber being defined between a tubular body defining a cylindrical cavity and the external surface of an open-end tubular diaphragm extending coaxially of the cavity, and a solid mandrel extending coaxially within each tubular diaphragm, each mandrel providing support surfaces for the diaphragm, the support surfaces extending axially of and being angularly spaced relative to the axis of the respectivediaphragm to define axially extending spaces therewithin, the tubular bodies having their axes parallel to the drive shaft axis and having a one-way inlet valve and a one-way outlet valve at the respective ends of the cylindrical cavity and communicating with the interior of said diaphragm and the spaces therewithin, each pressure chamber and associated cylinder being adapted to be filled with liquid whereby upon rotation of the drive shaft, liquid will be displaced between the pressure chambers and their associated cylinders by displacement of the pistons, causing the cross sectional areas of the diaphragms to vary thereby to vary the volume and the pressure within the diaphragms to cause displacement of liquid therethrough.

2. A pump according to claim 1 wherein each diaphragm is unstressed when in a cylindrical form.

3. A pump according to claim 1 wherein each mandrel provides at least three angularly spaced support surfaces for the respective mandrel.

4. A pump according to claim 1 wherein each mandrel provides more than three angularly spaced support surfaces for the respective mandrel.

5. A pump according to claim 1 wherein each cylinder is formed by a tubular extension extending radially from the respective tubular body.

6. A pump according to claim 1 wherein the means for reciprocating the pistons includes an eccentric member fast with the drive shaft an annular member coaxial with the eccentric and rotatably mounted thereon, the pistons being coupled to the annular memher.

7. A pump according to claim 1 wherein the one way valves include a ball and a seal therefor.

8. A pump according to claim 1 wherein the diaphragm is made of one ofa group comprising rubber, synthetic plastics and an elastomer.

9. A diaphragm pump comprising a drive shaft, a plurality of cylinders whose axes are equi-angularly spaced about the drive shaft axis and each of which axes is nor mal to the drive shaft axis, a piston received by each cylinder and reciprocable by an eccentric member coupled to the drive shaft, each cylinder being formed by a tubular extension of a tubular body defining a cylindrical cavity and being in communication with a pressure chamber, each pressure chamber being defined between the tubular body and the external surface of an open-ended tubular diaphragm received by the tubular body and extending coaxially of said cavity, and a solid mandrel extending coaxially withineach tubular diaphragm, each mandrel providing at least three support surfaces for the diaphragm, the support surfaces extending axially of and being angularly spaced relative to the axis of the respective diaphragm to define axially extending spaces therewithin, the tubular bodies having their axes parallel to the drive shaft axis and having a one-way inlet valve and a oneway outlet valve at the respective ends of the cylindrical cavity and communicating with the interior of said diaphragm and the spaces therewithin, each pressure chamber and associated cylinder being filled with liquid whereby, upon rotation of the drive shaft, liquid will be displaced between the pressure chamber and their associated cylinders by displacement of the pistons, causing the cross sectional areas of the diaphragms to vary thereby to vary the volume and the pressure within the diaphragms to cause displacement of liquid therethrough.

10. A pump according to claim 9 wherein the diaphragm is made of one of a group comprising rubber, synthetic plastics and an elastomeric material.

11. A diaphragm pump comprising:

a body defining a cylindrical cavity,

an open ended tubular diaphragm in the cavity, extending coaxially thereof and defining with the body a pressure chamber,

a cylinder coupled to and in communication with the pressure chamber,

.a piston received by the cylinder, 1

means for reciprocating the piston in the cylinder,

a one-way inlet valve and a one-way outlet valve at respective opposite ends of the cavity, coaxial with the cavity and communicating with the interior of the diaphragm,

a solid mandrel extending coaxially within the diaphragm, extending between the inlet and outlet valves and providing support surfaces for the diaphragm, which support surfaces extend axially of the diaphragm from the inlet valve to the outlet valve and define axially extending spaces therebetween and in communication with the inlet and outlet valves,

whereby when said pressure chamber and cylinder are filled with a fluid and said piston is reciprocated, fluid will be displaced back and forth be tween the pressure chamber and the cylinder, thus causing the diaphragm to alternately expand and compress said spaces, so that fluid to be pumped will be alternately drawn into said spaces through the inlet valve and expelled from said spaces through the outlet valve.

member fast with the drive shaft and an annular mem' ber coaxial with the eccentric and rotatably mounted thereon, the pistons being coupled to the annular member.

16. A pump according to claim 11 wherein the one way valves include a ball and a seal therefor.

17. A pump according to claim ll wherein the diaphragm is made of one of a group comprising rubber,

synthetic plastics and an elastomer. 

1. A diaphragm pump comprising a drive shaft, a plurality of cylinders whose axes are equi-angularly spaced about the drive shaft axis and each of which axes is normal to the drive shaft axis, a piston received by each cylinder and reciprocable by means coupled to the drive shaft, each cylinder being in communication with a pressure chamber, each pressure chamber being defined between a tubular body defining a cylindrical cavity and the external surface of an open-end tubular diaphragm extending coaxially of the cavity, and a solid mandrel extending coaxially within each tubular diaphragm, each mandrel providing support surfaces for the diaphragm, the support surfaces extending axially of and being angularly spaced relative to the axis of the respective diaphragm to define axially extending spaces therewithin, the tubular bodies having their axes parallel to the drive shaft axis and having a one-way inlet valve and a one-way outlet valve at the respective ends of the cylindrical cavity and communicating with the interior of said diaphragm and the spaces therewithin, each pressure chamber and associated cylinder being adapted to be filled with liquid whereby upon rotation of the drive shaft, liquid will be displaced between the pressure chambers and their associated cylinders by displacement of the pistons, causing the cross sectional areas of the diaphragms to vary thereby to vary the volume and the pressure within the diaphragms to cause displacement of liquid therethrough.
 2. A pump according to claim 1 wherein each diaphragm is unstressed when in a cylindrical form.
 3. A pump according to claim 1 wherein each mandrel provides at least three angularly spaced support surfaces for the respective mandrel.
 4. A pump according to claim 1 wherein each mandrel provides more than three angularly spaced support surfaces for the respective mandrel.
 5. A pump according to claim 1 wherein each cylinder is formed by a tubular extension extending radially from the respective tubular body.
 6. A pump according to claim 1 wherein the means for reciprocating the pistons includes an eccentric member fast with the drive shaft an annular member coaxial with the eccentric and rotatably mounted thereon, the pistons being coupled to the annular member.
 7. A pump according to claim 1 wherein the one way valves include a ball and a seal therefor.
 8. A pump according to claim 1 wherein the diaphragm is made of one of a group comprising rubber, synthetic plastics and an elastomer.
 9. A diaphragm pump comprising a drive shafT, a plurality of cylinders whose axes are equi-angularly spaced about the drive shaft axis and each of which axes is normal to the drive shaft axis, a piston received by each cylinder and reciprocable by an eccentric member coupled to the drive shaft, each cylinder being formed by a tubular extension of a tubular body defining a cylindrical cavity and being in communication with a pressure chamber, each pressure chamber being defined between the tubular body and the external surface of an open-ended tubular diaphragm received by the tubular body and extending coaxially of said cavity, and a solid mandrel extending coaxially within each tubular diaphragm, each mandrel providing at least three support surfaces for the diaphragm, the support surfaces extending axially of and being angularly spaced relative to the axis of the respective diaphragm to define axially extending spaces therewithin, the tubular bodies having their axes parallel to the drive shaft axis and having a one-way inlet valve and a one-way outlet valve at the respective ends of the cylindrical cavity and communicating with the interior of said diaphragm and the spaces therewithin, each pressure chamber and associated cylinder being filled with liquid whereby, upon rotation of the drive shaft, liquid will be displaced between the pressure chamber and their associated cylinders by displacement of the pistons, causing the cross sectional areas of the diaphragms to vary thereby to vary the volume and the pressure within the diaphragms to cause displacement of liquid therethrough.
 10. A pump according to claim 9 wherein the diaphragm is made of one of a group comprising rubber, synthetic plastics and an elastomeric material.
 11. A diaphragm pump comprising: a body defining a cylindrical cavity, an open ended tubular diaphragm in the cavity, extending coaxially thereof and defining with the body a pressure chamber, a cylinder coupled to and in communication with the pressure chamber, a piston received by the cylinder, means for reciprocating the piston in the cylinder, a one-way inlet valve and a one-way outlet valve at respective opposite ends of the cavity, coaxial with the cavity and communicating with the interior of the diaphragm, a solid mandrel extending coaxially within the diaphragm, extending between the inlet and outlet valves and providing support surfaces for the diaphragm, which support surfaces extend axially of the diaphragm from the inlet valve to the outlet valve and define axially extending spaces therebetween and in communication with the inlet and outlet valves, whereby when said pressure chamber and cylinder are filled with a fluid and said piston is reciprocated, fluid will be displaced back and forth between the pressure chamber and the cylinder, thus causing the diaphragm to alternately expand and compress said spaces, so that fluid to be pumped will be alternately drawn into said spaces through the inlet valve and expelled from said spaces through the outlet valve.
 12. A pump according to claim 11 wherein each mandrel provides at least three angularly spaced support surfaces for the respective mandrel.
 13. A pump according to claim 11 wherein each mandrel provides more than three angularly spaced support surfaces for the respective mandrel.
 14. A pump according to claim 11 wherein each cylinder is formed by a tubular extension extending radially from the respective tubular body.
 15. A pump according to claim 11 wherein the means for reciprocating the pistons includes an eccentric member fast with the drive shaft and an annular member coaxial with the eccentric and rotatably mounted thereon, the pistons being coupled to the annular member.
 16. A pump according to claim 11 wherein the one way valves include a ball and a seal therefor.
 17. A pump according to claim 11 wherein the diaphragm is made of one of a group comprising rubber, synthetic plastics and an elastomer. 